1. Field of the Invention
The principles of the present invention generally relate to flat light-emitting lamps, methods of fabricating flat light-emitting lamps, and liquid crystal displays using such flat light-emitting lamps. More particularly, the principles of the present invention relate to a high efficiency, flat light-emitting lamp having a reduced thickness, methods of fabricating such a flat light-emitting lamp, and liquid crystal displays using such a flat light-emitting lamp.
2. Discussion of the Related Art
Various types of flat panel displays such as liquid crystal displays (LCDs), field emission displays (FEDs), plasma display panels (PDPs), light emitting diode (LED) displays, and the like, have been developed as alternatives to cathode ray tubes (CRTs), which are heavy and occupy large amounts of space. LCDs, in particular, are widely incorporated within devices for use as monitors of notebook computers, spacecraft, airplanes, etc.
Transmissive LCD devices typically include an LCD panel and a backlight unit having a light source (e.g., a cylindrical fluorescent lamp). The LCD panel displays pictures by selectively transmitting light emitted by the backlight unit. Backlight units inherently increase the weight, thickness, and power consumption characteristics of any LCD device it is incorporated within. Depending on the location of the light source with respect to the LCD panel, backlight units can be generally classified as either direct-type or edge-type.
Edge-type backlight units generally include a fluorescent lamp provided along a lateral side of a light-guide plate that is disposed beneath an LCD panel. The light-guide plate diverts light emitted by the fluorescent lamp from its lateral side to a backside of the LCD panel to uniformly transmit the emitted light into the LCD panel. Because light emitted by the fluorescent lamp must be diverted and transmitted by the light-guide plate, LCD devices incorporating edge-type backlight units undesirably display pictures at a low brightness. Moreover, edge-type backlight units tend to require complex optical designs and processing technologies to successfully divert and transmit light of a uniform intensity to the LCD panel.
Direct-type backlight units generally include a plurality of fluorescent lamps (or one bent fluorescent lamp) provided beneath an LCD panel. Unobstructed, the light transmitted by the LCD panel undesirably forms an image on the LCD panel in the same shape as the fluorescent lamp. Therefore, the fluorescent lamp is typically spaced apart from the LCD panel by a predetermined amount and a light-diffusion sheet is disposed between the LCD panel and the fluorescent lamp to ensure that the LCD panel is illuminated with light having a uniform intensity. Due to the construction outlined above, it is difficult to form direct-type backlight units that are thin. Accordingly, much effort has recently been made to research and develop a flat light-emitting lamp having a flat panel shape that is disposed adjacent to an LCD panel.
Moreover, in Korean Patent Laid-Open No. P2002-0085238 (Nov. 16, 2002), a backlight unit, provided as a plasma lamp, was proposed. While such a plasma lamp is thin and has a high brightness, an internal pressure between the upper and lower glass substrates of the plasma lamp is lower than the external, atmospheric pressure. Therefore, the substrates must be sufficiently thick to prevent the plasma lamp from breaking. However, as the thickness of the glass substrates increases, the weight of the plasma lamp undesirably increases. Moreover, ball- or cross-type spacers/barrier ribs must be provided between the upper and lower substrates to support the substrates across a wide area. Upon incorporating such spacer/barrier ribs, the overall thickness of the plasma lamp increases. Moreover, heat generated during operation of the plasma lamp undesirably shortens the lifetime of the plasma lamp.